Electrothermostatic apparatus



Dec. 8, 1936. T, J SMULSK] 2,063,705

ELECTROTHERMOS TATI G APPARATUS Filed April 21, 1930 l 2 Sheets-Sheet 1 Dec. 8, 1936. J sMuLsKl 2,063,705

ELECTROTHERMOSTAT IC APPARATUS Filed April 21, 1930 2 Sheets-Sheet 2 Patented Dec. 8, .1936

UNITED STATES PATENT OFFICE Anderson Company, of Indiana Application April 21,

Claims.

My invention relates to electro-thermal apparatus and relates particularly to electro-thermal apparatus adapted for operation in pairs comprising a controlled and controlling apparatus for any useful purpose wherein simultaneous commensurable operation of a controlling and controlled apparatus is required.

The apparatus of my present invention is susceptibie of operation according to the modes set forth in the following patents: Patent No. 1,885,- 050 to Theodore J. Smulski, Patent No. 1,885,051 to Theodore J. Smulski, Patent No. 1,885,048 to Frank M. Slough, all of which issued on October 25, 1932.

It is an object of my present invention to provide improved efllcient apparatus operable according to the principles as generally set forth in said patents.

Another object of my invention is to provide an improved controller for telegraphing electrical impulses to suitable controlled apparatus, thereby operated commensurably to the temperature of a body with which the controlling apparatus is associated.

Another object of my invention is to provide improved electro-thermal apparatus wherein the thermal properties of the apparatus may be elliciently predetermined in the quantity production of the apparatus.

Another object of my invention is to provide improved apparatus for indicating temperatures remotely from the manifestation of the temperature effect to be indicated.

Another object of my invention is to provide certain features of improvement in apparatus of the general type to which my invention relates, which will be more apparent from the following description of certain embodiments of my invention wherein reference is had to the accompanying drawings illustrating the said embodiments.

Referring to the drawings:-

Fig. 1 is a side elevational view of an indicator mechanism which may advantageously be employed in the said system embodying my invention;

Fig. 2 is a plan view of the mechanism of Fig. 1, the view showing the indicator dial and movable hand therefor;

Fig. 3 is a side elevational view of the indicating mechanism of Fig. 1 taken from a position at right angles to that from which the view of Fig. 1 is taken;

Fig. 4 is a bottom plan view of an insulating mounting plate for the said indicator mechanism;

Gary, Ind, a corporation 1930, Serial No. 445,994

F18. 5 is a section taken on the line 5-4 of Fig. 1;

Fig. 6 is a longitudinal medial sectional view of compensated thermostat mechanism and heating element therefor, together with associated parts relating to the indicating apparatus of Figs. 1 to 5, inclusive;

Fig. 7 is an elevational view of a controlling apparatus embodying the principles of my invention;

Fig. 8 is a longitudinal medial sectional view of the apparatus of Fig. 7 taken along line 88 of Fig. 7;

Fig. 9 is an end plan view of the controlling apparatus of Fig. 7, with a cover cap therefor removed;

Fig. 10 is a plan view of the apparatus of Fig. 7 with the cover cap in position;

Fig. 11 is a diagrammatic view of the controlling and controlled apparatus of'the foregoing figures and an operative electrical system in which such apparatus is included;

Fig. 12 is a front elevational view and Fig. 13 a longitudinal medial sectional view of an indicating apparatus which is another embodiment of my invention;

Figs. 14 and 15 show, respectively, a front elevational and longitudinal medial sectional view of another form of indicating apparatus, but with the front dial plate and casing removed, which is another embodiment of my invention;

Fig. 16 is a view similar to that of Fig. 14 and Fig. 17 a view similar to that of Fig. 15 of an indicator which is another embodiment of my invention;

Fig. 18 is a fragmentary section taken on the line ill-l8 of Fig. 17 showing an adjustable operative element of the mechanism of Figs. 16 and 17;

Fig. 19 is a longitudinal medial sectional view of a controlling apparatus which is another embodiment of my invention;

Fig. 20 is a section taken on the line 20-20 of Fig. 19 and Fig. 21 is a side elevational view of an operative element of the apparatus of Fig. 11.

Referring now to Figs. 1 to 6, inclusive, in which a form of the indicating mechanism of the system is illustrated, the parts shown may be mounted on a mounting plate l8 of insulating material. A pair of posts I!) secured to and extending in parallel relation from the support 18 carry a dial plate 20 secured to the posts by screws 2|. The dial plate, preferably, is marked with dial lndicia 22, some of the spaced marked divisions thereof being provided with numerals, which may, for instance, refer to degrees of temperature, Fahrenheit. The pointer hand is supported by a thermostat comprising a pair of reversely coiled helices 23 and 24, which are integrally joined together by the contiguous ends 23 of the helices disposed in the form of a loop.

The two helices are axially aligned and preferably longitudinally spaced with a baiiie plate 23 of heat insulating material, preferably disposed between the two to restrain the flow of heated air from the helix 24 to the helix 23, and from the heating element 21 which is axially disposed within the helix 24 for the purpose of heating it when the device is in operation as later herein described.

The bai'iie plate 23 is supported on a bracket 31 which is rigidly secured on the insulating base i3 by a screw 33 projected through the base of said bracket and said plate. The nuts 33 on the outermost end of the screw 33 provide a binding post for making connection by circuit conductors with the screw 33 and therefore with the bracket 31 to which a terminal of the heating element 21 is permanently connected.

The pointer 43 is secured to the outermost coil of the helix 23 in any suitable manner, such as by soldering the disk 23 to the center of which the pointer 43 is affixed, to the outermost convolution of the helix, or by effecting a frictional engagement therebetween. The hand 43 is joined to the disk 28 by a short arm I I2 of the hand projected through an arcuate opening SI of the dial plate. The remote end of the helix 24 terminates in a convolution 29, preferably formed as an annulus and rigidly aflixed to a hollow screw 33 which is screwthreaded within the bore 3| of the insulating supporting plate is. The screw 3| may have a screw driver receiving slot as shown at 32.

The heating element 21 is axially suspended within the helix 24, being in the form of a resistance wire helix and is maintained in position by its leading-in wires 33 and 34 projected through the axial bore of a bored insulating plug 35 and an axially disposed aperture 36 of the baiiie plate 26.

A preferably copper circuit conductor 40 of substantial gauge and a like circuit conductor 4| are joined to the leading-in wires 33 and 34, respectively, and are respectively connected to the similar binding posts 42 and 39, respectively, the latter through the bracket 31 to which the conductor 4i is preferably connected.

From the foregoing description, it will be understood that the helices 23 and 24 being oppositely wound and alike in the number of their convolutions and other dimensional characteristics and each being formed of a ribbon of bi-metallic material, upon changes of temperature will tend to wind or unwind, in a manner well known for such helices, but in opposite directions and to the same degree, whereby for all ambient temperatures, any tendencies toward rotative movement of the hand 43 resulting from such changes of temperature will be thoroughly compensated, each of the helices compensating for the other.

However, only the helix 24 is exposed to the effect of electrical heating, being provided with the electrical heating element 21 axially telescoped within it, and heat therefrom being prevented as by the guard 26 from reaching the helix 23. When the heating element 21 is energized, the helix will tend to unwind to produce a rotative movement of its arm 25 and therefore of the carried helix 23 which supports the hand supporting disk 23. As a result of this electrical heating action, the hand 43 will'advancealong the scale 22 toward the left from its starting position at the right side of the dial.

- In calibrating the instrument, should it be found that the heating helix 21 produces more than the predetermined amount of heat, and therefore deflects the needle 43 to an excessive degree, the portion of the helix 21 disposed within the thermostat helix 24 may be reduced by grasping the circuit conductor 43 with a suitable tool and pulling'the leading-in wire 33 to draw some of the wire of the heating element 21 into and/or through the bore of the insulating plug 33 to reduce the length of the heating element disposed within the thermostat helix. Such an adjustment may be employed where great accuracy is required and as a final adjustment.

The helix 21 is preferably wound with considerable closeness between the successive convolutions which are of a small diametrical dimension so that the mass of the heating element per cubic inch of space occupied is relatively large. This arrangement is conducive toward providing a substantial amount of heat storage capacity in the helix 21, whereby the helix will not rapidly lose its heat between impulses of heating electrical current directed through the helix.

Referring now to the controller of Figs. 7 to 11, inclusive, and Fig. 2i, the controller, preferably, provides a metal tubular heat conducting support having a hexagonal head I, a reduced intermediate portion 2 and a longitudinally extending tubular tip 3 having an integral end closure 4. The bore 5 of the support extends axially therethrough and is of such a diameter as to receive the double thermostatic element of Fig. 21 telescoped preferably axially therein with its annular end 6 integrally united as bv solder 1 to the metal end 4 of the support with the outer surfaces of its convolutions disposed in substantial air spaced relation to the inner walls of the tubular support. The helical thermostat is formed of a strip of thermostatic bi-metallic material, the inner surface of which comprises a metallic strip of a metal having a diflerent coefficient of thermal expansion than a seccnd strip of metal integrally secured by a face to the inwardly disposed strip.

The composite strip thus formed is given the form of a helix having longitudinally aligned sections, each section of which is reversely wound relative to the direction of winding of the other.

One of the sections, namely the section 3 terminating in the annulus 6, as above stated, is relatively longer, contains more convolutions, and the total length of bi-metallic strip forming said convolutions is greater than the number of convolutions and aggregate length of the convolutions of section 9, for a purpose to be later explained. The sections are integrally joined together by a substantially U-shaped portion of the strip shown at III, which is stiffened against bending by providing it with an out-turned tip I I, see especially Fig, 21.

To the end convolution i2 of the shorter thermostat section 9, formed as described, a pair of diametrically oppositely disposed prongs I! are preferably provided to which, as shown in Figs. 7, 8, 9 and 11, a metallic cross arm I4 is soldered and projects laterally to one side of the two prongs to terminate in a contact carrying arm I6 supporting an electrical contact element l1.

Prior to placement of the cross arm I4 on the ace-ence prongs, a disk 48 of preferably electrical and heat insulating material is affixed to the hexagonal head i of the tubular support by the provision of a tubular flange 44 whose bore is of the same diameter as the bore 5, projecting integrally from said head and terminating in 'a slightly outturned end 45. Forced into the material of the insulating disk 43 preferably a metal washer 48 is fitted over the flange 44. Prior to expanding its end 44 to the form shown, the disk 48 is circum ferentially relieved near its outer end for the reception of the lateral cylindrical walls 41 of a cover cap 48 telescoped over the outer surface of the said relieved disk portion. Suitable means, such as the screws 48, may project through suitable apertures of the walls 41 into suitably placed threaded recesses of the disk 43 to rigidly secure the cap 48 on the disk.

Supported on the inner face of the disk 48 I provide a tube 58 of glass or other heat resistant material secured to the disk by press fitting its end 5| into a centrally disposed recess of the inner wall of the disk. In longitudinal alignment and communicating with the bore of the glass tube 58 I provide a passage 52 extending from the bore of the tube 50 to the opposite surface of the disk for the reception of an electrical circuit conductor 53 projected through said passage 52 and through the longitudinal bore of the glass tube 58 to its free end where the conductor 53 is reversely turned and connects, integrally or otherwise, with the heat producing electrical circuit conductor 54, helically wrapped from the free end of the tube 58 toward its flxed end on its outer surface.

The glass tube 58 is of such reduced diameter relative to the internal bore of the shorter helix 9, as to be substantially air spaced therefrom and the length of the tube, and therefore of the heating element winding 54, is preferably somewhat less than the length of the helix 8. In preparing the helices 8 and 8, I preferably make the innermost material that which has the greatest coefficient of thermal expansion.

An afflxed contact support 68, in the form of a metal post, is mounted on the outer surface of the disk 43, said post, preferably, projecting into the material of the disk by a stem portion, not shown. The post supports a contact screw 55, screwthreaded' transversely through it, said screw being provided with a tip contact 58, on its end adapted for engagement with the movable contact I! carried by the contact arm It. By turning the screw 55 the fixed contact 56 may be adjusted relative to a given position of the movable contact I! so as to vary the rotative position of engagement between said contacts.

A bridge 51 secured at its ends to the disk 43 by screws 58 overlies the center of the disk, and also the cross arm H. The cross arm l4 carries a pinion rod 59 disposed in axial alignment with the axis of the helices 8 and 8, and projects through a journal opening 8| extending centrally through the bridge 51.

In this manner, the helices 8 and 8 and the contact carrying arm l6 are held in proper position relative to the axis of the device, the crossarm l4, which terminates in the contact arm ll rotating on the pinion 59 centrally journalled in the bridge 51, to rotatablymove its carrying contact I! on a given radius toward and away from the fixed contact 58 adapted for engagement thereby.

A binding post is rigidly mounted in the insulating materialof the disk 43, and projects from its outer face through an aperture 82 of the cover cap 48, but escaping contact therewith by reason of the relatively large size of the aperture 42. The

upper end of the electrical heating resistance helix 54 joins with a circuit conductor 88, which is electrically connected to the binding post 80.

The operation of the controller, above described, will be readily understood by reference to the flgures described and by collateral reference to Fig. 11, showing diagrammatically an electrical system in which the indicator apparatus of Figs. 1 to 6 is shown as included, and op erable under the control of the described controller. The system and apparatus operate as follows: It being understood that the tubular support is screw threaded by its exteriorly threaded intermediate portion 2 into a wall of a fluid conduit, the variable temperature of the fluid .contained therein being that variable factor, the quantitative values of which are desired to be indicated remotely of the controller at the indicator having the indicating hand or needle 43, with the closed tubular end 3 projecting into said fluid.

For example, it may be assumed that the tubular end 8 is thus projected into the cooling water of an automotive engine water cooling jacket and the temperature of such water is thermally conducted by the' end wall 4 of the tube to the annular end 6 of the bi-metal helix 8, which is thereby heated to a temperature approximately that of the temperature of water in the jacket.

The temperature of the water or other fluid in contact with the tip 3 of the support is communicated to the interior thereof and will heat the helices 8 and 8. The helix 8 is provided with a greater length of bi-metallic strip material than the helix 9 and when heated to the same temperature as the helix 8 will effect a greater rotary movement of its end ill in one direction than will be effected by the helix 9 upon the prongs l5 carried at its free end, and since the prongs l5 are carried by the free end of the helix 8, the combined opposite rotary efiects of heating the helices 8 and 8 simultaneously will be to move the prongs l5 in a rotary path about the axis of the helices 8 and 9 an amount which represents the amount of rotary movement of the end in of the helix 8, which is in excess of that effected by the helix 8 upon the prongs I5.

Therefore, by the excess of rotary movement effected by the helix 8, the prongs l5 will be moved to carry the contact carrying arms It to move the contact I! in a rotary path to effect engagement between the contact I! and the fixed contact 56, which is mounted on a post 68. Since engagement is had between the contacts 58-41, an electrical circuit is closed which in the embodiment of Fig. 11 may be traced from the source of current S, such as a storage battery through the closed switch SW, the indicator heating element 21, circuit conductor H3, the connector post 88, the conductor 63, the controller heating element 54, the conductor 53, the supporting post 88, the contacts 58-, now in engagement the arm i8 and I4, the prongs l5, the integrally joined helices 8 and 8 and thence through the grounded frame of the water jacket supporting the tubular support by its portion 2 to the grounded pole ofthe source of current S.

Current flowing over the circuit just traced, will effect simultaneous heating of the elements 21 and 54, at the indicator and controller, respectively, to cause a rotative movement, respectively, of the indicator hand 43, and the contact carrying arm l8. By supplying additional heat from the heating element 54, principally to the helix 9 and largely excluding the communication of heat therefrom to the helix 8, will cause the helix 9, although of shorter length and containing fewer convolutions and therefore being less responsive than the helix 8 when at the same temperature, to respond additionally because of its increased temperature to move the prongs l5 in the opposite direction to that above described, in other words in a clockwise direction, as viewed in Fig. 9, until the contacts l! and 56 are separated. Separation of these contacts will not occur until the heating element and the helix 9, taken together, have accumulated sufficient heat, so that "IE u1- timate temperature effected by the helix 9 is sui flcient to cause it to respond thermostatically to move its free end sufliciently to break the contacts. An appreciable period of heat is thereby effected and in addition, even after the instant when the contacts ll--56 are broken, heat will continue to be supplied to the helix 9 from the heated element 54 even though it has started to lose some of its heat, so that the contacts lT--58 will be separated an appreciable distance, until the communication of heat to the helix 9 has become discontinued.

Since the circuit is thus broken, however, cooling of the heating element 9 will be effected gradually until the heat electrically effected in the helix 8 will produce a. lesser rotative effect than that produced in the helix 8 by heat received from the fluid, and the contacts Il-SG will be reclosed.

This operation will be periodically continuous and will effect a periodic closure of the contacts and resultant periodic flows of current through the two heating elements, which will be thus supplied wlth increments of heat periodically simultaneously.

Both heating elements are so disposed and with their associated parts possess a sufllcient ability to store heat, only partially lost during non-heating periods, whereby neither of the electrically heated controlling helix 9 and controlled helix 24 are greatly cooled during non-heating periods.

As a result the indicator hand 43 having taken a given positon on its associated scale will oscillate but slightly from such position and the mass and material composing said heating element and its associated parts relative to the radiating surface thereof is made such that it may be heated in a sufilciently short time to effect an indicator hand movement to indicate a given temperature telegraphed from the controller and will substantially maintain such indication while the current over the electrical circuit is commutated periodically by the contacts l1-56.

The adjustment screw 55 for the controller may be rotated to longitudinally move its carried contact 56 to position the hand 43 at any desired point on the scale, for any given temperature of the fluid supplying heat to the helix 8. The glass tube 50 may be spirally grooved to receive in such groove the electrical resistance wire 54 to predetermine its length and position, or any other suitable means may be provided to insure this effect.

It will be understood that since the helix 9 01 the controller is shorter than the helix 8, more heat will be required to be supplied to it by the electrical circuit conductor 54 than the heat supplied to the helix 8 to accomplish a given movement of the contact l1. Also, heat from the fluid will be transmitted to a considerable extent to the helix 9, as well as the helix 8, subtracting by its effect on the helix 9, from the primary actuating movement effected on the contact I l by heating of the helix 8.

The helix 8, however, is given a sufficiently greater number of turns, so as to overcome this mechanical handicap when heated by the fluid, so that actuation of the contacts is assured.

The electrical heating element 54 supplies sufllcient heat to the helix 3, additional to that supplied from the fluid medium, so that the helix I becoming hotter than the helix 8 and maintained at a greater temperature, while the heating element 54 is heated, insures that the contact I! may be moved from engagement with the contact 50 afterheating of the element 54 has progressed for a predetermined short time, during each heating period.

It will be understood that for greater values of temperature of the liquid in the water jacket, or other fluid medium, the total length of heating periods in a given time, relative to non-heating periods, will be commensurably increased, so that the total amount of heat supplied to the heating element 21 in a given short time, that is the rate of heating of the element 21, will be increased.

It will be understood, also, that the indicator hand 43 will take variable positions commensurable with the intensity of the heat during each heating period and the length of such heating period, and the relative length of heating periods to non-heating periods, that is to the rate of heating.

Referring now to Figs. 12 to 15, inclusive, which show an indicator mechanism which is another embodiment of my invention, operating substantially like that shown in Figs. 1 to 6, inclusive, in such other embodiment, a. pair of longitudinally aligned and spaced spirally formed thermostat elements 65 and 66 are provided, Joined together by a yoke 61 uniting their outer ends. The central portion of the spiral BI is rigidly secured to a fixed hub l6! adjustably rotatable in a heat insulating support 69, and the central portion 01' the spiral 65 carries a hub III, which is rotatably journalled on a Journal pin 1| rigidly carried on a second support 12, which is preferably spaced from the support 69, both being preferably secured to opposite sides of a. spacer II.

The indicator apparatus, so far described, is secured by its supporting spacer element 13 to a lateral wall of a tube 14, which in turn is carried by an end wall of a preferably metallic shallow cup 15, apertured at 16 to receive the end of the tube 14, which is rigidly secured to the cup end wall by making a press fit therewith and/or by soldering the contiguous surfaces of the tube and cup end wall. The lr'b projects by a. reduced end 11 into the cup 15, the inner surface of whose end wall is provided with dial containing facing 18, having suitable dial scale divisions and indicating indicia therefor, shown at 19, said face being suitably apertured, as at 80, whereby the hub 10 may project therethrough.

A dial glass 8| is carried on the rim of the cup and held in place by an inwardly flanged tubular clamping annulus 42 held in place by screws 83. An electrical heating element consisting of a grid 84 of resistance wire, is carried on the inner face of a plug 85, screwthreaded into the end of the tube 14, being bored to permit the terminal conductors 85 of the heating element to project to the outer face of the plug for connection to suitable electrical terminals II, as shown.

The air spacing between the heating element grid 04, and the adjacent spiral "is susceptible 7 same length to the same degree to neutralize or to compensate each other for, ambient temperatures.

Upon the heating element 04 being energized by flow of current therethrough under conditions, for instance like that shown in Fig. 11, for the heating element 21, the inner surfaces of 'the convolutions of the bi-metallic convolutions of the spiral 66 being of the more expan'sible material, rotation of the hub 11 carrying theindicator hand 89 will be effected to move the point of the hand over the scale I9 toward the right. The apparatus, as described, is provided for the same purposes and operates in the same manner as described in the embodiment for Figs. 1 to 6, inclusive.

In the embodiment of Figs. 14 and 15, a modification from that shown in Figs. 1 to 6, inclusive, is shown, whereby the heating element 21' telescoped within the helix 24' 'is susceptible of being longitudinally adjusted by an adjusting screw 09 screw-threaded in an opening of the insulating base I8, and therefore, movable longitudinally by rotating it. In this embodiment, the heating element 21' includes a rod of glass or like material supported between the end of the screw and the resilient heat insulating guard 26'.

From the above description, it will be understood that rotation of the screw 89 will longitudinally displace the heating element relative to the convolutions of the thermostatic helix 34', and therefore to vary the amount of heat communicated from the heat element to the convolutions of said helix.

This provides a manufacturing adjustment.

which may be substituted for the expedient of drawing some of the wire of the heating element, such as 21, Fig. 3, from the helix. In this embodiment, also, a sheet metal frame is provided for supporting the relative parts of the mechanism on the base I9, said frame comprising standards I 9' adapted to support a dial plate, as that shown at 20, Figs. 3, 4 and 6, instead of the posts I9 shown in Figs. 3 and 4.

Figs. 16 to 18, inclusive, illustrate another embodiment indicator, which difiers principally from that shown in Figs. 14 and 15 in that the bi-metallic material providing a pair of relatively compensating thermostat elements 24" and 23" comprise only one convolution, which is joined by an intermediate substantially V-shaped loop 25", which is stiffened longitudinally of the thermostats by bending it longitudinally, as shown at 90 and 9I, so that lateral warping in this part of the thermostat will not occur to any appreciable degree. The hand 43 is preferably soldered, as shown at 92 to the free end of the compensating thermostat portion 23".

The heating element 29' and the adjustment screw 89' substantially corresponds to the corresponding elements of Fig. 15. A support for the thermostatic elements of Figs. 16 to 18, inclusive, is provided by a plate 93, arcuately slotted at 94 providing an upstanding flange 95 to which the fixed end 96 of the thermostat element 24" is afllxed, preferably by soldering.

An adjustment screw 91 projected through the slot 94 into a supporting base 90 is effective to retain the unitary element comprising the plate 99, the thermostatic elements 20" and 23 and the hand 49" in a given rotative position of adjustment wherein the hand 43 takes a given position relative to the dial scale upon a given electrical energization imparted to its heating element 21".

Referring now to the-embodiment controller shown in Figs. 19 and 20, this embodiment is provided with elements generally corresponding to those of the embodiment of Figs. '7 to 11, inelusive, with the following exceptions. For the tube comprising stepped sections I, 2 and 3, a sheet metal tube 99 is provided to the end wall of which the fixed end of the bi-metallic helix 8 is affixed, the tube 99 terminating in an enlarged cup portion I forming a part of the casing for the elements consisting of the movable contact I1 and the fixed contact 56. The fixed contact is carried on a post 54 secured by a stem I0! to an inverted cup-shaped element I02 of insulating material, a reduced portion of whose tubular lateral walls I03 is telescoped snugly within the lateral walls of the cup-shaped end I00 of the tube 99.

Besides the thermostatic helix 8', an electrically heated helix 9, shorter in length and longitudinally aligned disposed relative thereto, is provided as in the foregoing embodiment referred to, and a preferably helical heating element 54 of resistance wire carried on a rod 50 is telescoped within the helix 9. The two helices 8 and 9' are joined by their adjacent ends by a yoke I0 in the form of a wire rod. As in the foregoing case, the two helices are wound in opposition. The rod 50 is rigidly fixed within a central bore of the insulating cover cap I02. The cover cap I02 is bodily rotatable to rotatably adjust the fixed contact 56' for engagement with the thermostatically movable contact II. A set screw I04 through the lateral wall of the cup shaped end of the tube 99 holds the insulating cover cap I02 in any desired adjusted rotative position. The electrical heating element is joined by its two terminal circuit conductors to the fixed contact 54' and an electrical terminal element I consisting of a screw projected through the end wall of the cap I02 and a binding post nut disposed on the exterior side of the cap.

The device of Figs. 19 and 20 may be projected into any suitable opening in a wall of a fluid containing casing, or the entire device exposed to fluids, such as air, the temperature of which is adapted to be indicated by a remotely disposed indicator, such as any of those herein shown connected in electrical serial circuit with the controller of Figs. 19 and 20, together with the source of current, as shown in Fig. 11.

Having thus described my invention in various embodiment apparatuses, I am aware that numerous and extensive departures may be made from the apparatuses herein illustrated and described, but without departing from the spirit of my invention.

I claim:

1. In an electrical controller, a thermostat comprising a pair of substantially longitudinally aligned coils of bimetallic material joined to- "econd-named coil, said means conr flow oi electrical current through said heat g element by its rotary movement, an r of convolutions in the first coil than the number of convolutions 11 whereby the aforesaid rotary non-joined end of the second be effected by variations m. :al controller, a thermostat comof substantially longitudinally bimetallic material joined toof each, the winding from the 1 opposite directions, a support tat, one of said coil-s having its really supported by said support, ng' element disposed in thermal r of said coils, means receiving ill from the non-joined end of coil, said means controlling trical current through said heatrotary movement and operable cult to reduce the heat generated 1 element after an interval 01' heat- "ig and to close the circuit and increase the heat generated by the heating element after a period of cooling, said rotary movement being eiieoted by providing a different number of convolutions in the first and second coils whereby variations of ambient temperature will effect a differential rotary movement of the non-Joined end of the second named coil.

3. In an electrical controller, a thermostat comprising a pair of substantially longitudinal 35 aligned coils formed of bimetallic material integrally secured together at an end of each, one of said coils being fixedly supported at an end thereof and at its opposite free end forming a support for the other coil, an electric heater disposed axially of and in thermal relation to one of said coils, an electric circuit for the heater, the free end of said other coil being provided with a contact adapted to control the heater circuit upon movement of the coil contact in a rotary path due to coil temperature variations, and each coil having a different number of convolutions whereby the free end thereof will rotate in opposite directions for different amounts or the same temperature variations.

4, In an electric controller, a thermostat comprising a first thermally responsive element having one end fixed to a support and its opposite adapted to move in a given direction a predetermined amount responsive to a given temperature variation, 9. second thermally responsive element having one end movably secured to the said opposite end of the first element adapted o move in the opposite direction a difierent amount for the same temperature variation, whereby a differential movement or the tree end its second element will be effected by ambient temperature variations, an electric heater disosed in thermal relation to one or said elements, an electric circuit for the heater, the free end of the second element being provided with a contact controlling the heater circuit whereby a series oi. current impulses will be efiected in the circuit of a value in correspondence with ambient temperature.

5. The controller as described in claim 4, and wherein the thermally responsive elements are enclosed in a fluid-tight casing of heat conducting material, whereby the ambient temperature will substantially correspond to fluid temperature externally of the casing.

THEODORE J. SMULSKI. 

